Firefox: We talk a lot about privacy at Lifehacker, specifically about how your activities are tracked on the web and what you can do to stop it. If you're still on the fence or not convinced that the issue is as widespread as it is, Collusion is a Firefox extension that will show you in real time which sites are tracking you, where you picked up their tracking cookies, and what they can see.

It's no secret that there's big money to be made in violating your privacy. Companies…
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Collusion provides a visual, interactive map of tracking services you've interacted with and the sites you visited with the tracking cookies and scripts on them. Installing Collusion doesn't require a restart, and once installed, the add-on opens a tab and begins to draw a map of how you're being tracked as you browse the web. You'll find most sites use some kind of tracking cookies (ours included) for ads, stats, and social media, but even after a few minutes of web browsing, the tracking map can grow alarmingly large. Hover over any point on the map to see who the tracking service is, and which sites you've visited are connected to it.

Dots in red are services that PrivacyChoice has confirmed track you across multiple sites. Dots in grey are unconfirmed, and some of them are harmless (like Disqus, for example, which tracks you across sites so you can comment on articles,) but that doesn't mean they don't keep tabs on you. If you want a real picture of who has access to what information, just look at the list of sites associated with each dot. If you already have some tools installed to prevent this kind of tracking and want to quality check, Collusion can help you see how well they're working. If you're not doing anything and the sheer number of services tracking your activities has you concerned, check out our guide to making the web more opt-in than it is opt-out for some suggestions.